Frame construction with yieldable knee brace connection

ABSTRACT

A frame construction with a yieldable knee brace connection comprising a beam truss means having a top chord and a bottom chord, the top chord of said beam truss means supported at least at one end thereof adjacent the top of a vertically extending column means, at least one knee brace means connected to and extending from one end of the bottom chord to the adjacent side of said vertically extending column means, and means operatively associated with said knee brace means to absorb horizontal deflection of said bottom chord and thus prevent bending of said vertically extending column means.

United States Patent 1 Love et al.

[ Feb. 26, 1974 [73] Assignee: Butler Manufacturing Company,

Kansas City, Mo.

[22] Filed: May 2, 1972 [2,1] Appl. No.: 249,505

[56] References Cited UNITED STATES PATENTS 9/1972 Bowling et a1. 52/39311/1958 Cliff 52/693 X Fillion 248/15 X Alderman et al. 52/!67 X PrimaryExaminer-Price C. Faw, Jr. Attorney, Agent, or Firm-Shoemaker andMattare [5 7] ABSTRACT A frame construction with a yieldable knee braceconnection comprising a beam truss means having a top chord and a bottomchord, the top chord of said beam truss means supported at least at oneend thereof adjacent the top of a vertically extending column means, atleast one knee brace means connected to and extending from one end ofthe bottom chord to the adjacent side of said vertically extendingcolumn means, and means operatively associated with said knee bracemeans to absorb horizontal deflection of said bottom chord and thusprevent bending of said vertically extending column means.

10 Claims, 5 Drawing Figures PATENTEDHazs 1914 sum 1 [1F 2 FRAMECONSTRUCTION WITH YIELDABLE KNEE BRACE CONNECTION BACKGROUND OF THEINVENTION This invention relates to a means of connection between a beamtruss and its supporting columns to absorb-horizontal deflections ofsaid beam truss and thus prevent bending of said columns.

Conventional engineering practice in the design of buildings, as forexample, in the design of mill buildings, is to design the beam trussfor maximum vertical loading with the truss designed as a simplysupported beam. The columns on which the truss is supported are designedfor the resulting axial or vertical load thereon from the beam truss,and in order to provide resistance to side loading, such as wind loadingand the like, a brace is -added between the lower chord of the beamtruss and the adjacent side of the supporting column. Vertical loadingon the beam truss causes vertical displacement of at least the centerportion thereof and the lower chord of the beam truss is accordinglydisplaced horizontally toward the columns. The brace extending betweenthe bottom chord and the column resists this horizontal displacement andcauses a compressive force in the brace, thus bending the column.Frequently, this bending of the column is larger than that for which thecolumn is designed. It is common practice in the prior art to ignorethis over stressing of the column and to use compact'mill wide flangecolumns and design the trusses with. moments of inertia 80 to 100 timesgreater than that of the supporting columns. The resulting structure isa plastic design forming in effect a hinge in the columns at the bracelocation. The material in this localized region yields and flowsplacticallyto allow the required deformation of the columns withoutdamage thereto.

If non-compact fabricated H-section columns, and trusses with decreaseddepth and therefore less moment of inertia that those of conventionaldesign, are used in the building construction, then there is apossibility of over stressing of the columns.

By means of the present invention, the above problems are ecomonicallyand effectively solved. In the present invention a yieldable connectionis provided in operative association with the brace extending from thebottom chord of the beam truss to the adjacent side of the verticalsupport column. This yieldable connection absorbs the horizontaldeflection of the bottom chord and thus prevents bending of thesupporting column. More particularly, in accordance with the presentinvention, a yieldable deflection pad is interposed between the end ofthe brace and the adjacent side ofthe vertical column, and thisyieldable pad absorbs the horizontal movement of the bottom chord undervertical loading of the beam truss, thereby preventing bending of thecolumn. The pad is sufficiently rigid, however, to provide adequatebracing against side sway due to wind loading and the like.

The invention thus provides a frame construction which results in astructurally sound and economical column design for fabricatedI-I-section columns.

OBJECTS OF THE INVENTION It is an object of this invention to provide astructurally sound and economical frame design which permits the use offabricated H-section columns.

Another object of this invention is to provide a frame constructionhaving a beam truss means and supporting column means wherein a bracemeans extends from the bottom chord of the beam truss means to thesupporting column means and means is operatively associated with thebrace means for absorbing horizontal deflection of the bottom chord toprevent bending of the column means.

A further, object of this invention is to provide a frame constructionhaving a beam truss means with a top chord and a bottom chord andsupported on vertical column means, and wherein a knee brace means isconnected between the bottom chord and the adjacent side of said columnmeans with a yieldable deflection pad connected between one end of theknee brace and the adjacent side of a support column to absorbhorizontal deflection of said bottom chord due to vertical loading onsaid beam truss, and thus prevent bending of said column.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top perspective view witha portion broken away from a frame construction in accordance with thepresent invention.

FIG. 2 is a fragmentary view in elevation of a portion of the framemeans of FIG. 1, with the frame in unloaded condition.

FIG. 3 is a view similar to .FIG. 2 with the frame in loaded condition.I

FIG. 4 is a view in elevation of the frame means of FIG. 1 with a'vertical load applied to the beam truss.

FIG. 5 is a view similar to FIG. 4 of a prior art construction with avertical load applied to the beam truss and showing the bending of thevertical support columns.

DETAILED DESCRIPTION OF THE INVENTION In the drawings, wherein likereference numerals indicate like parts throughout the several views, aframe construction is indicated generally at F in FIG. 1 and comprises abeam truss T and supporting columns C. The beam truss T comprises a topchord 10 having a T- shaped cross sectional configuration and a bottomchord 11 having an inverted T-shaped cross sectional configuration. Thebottom chord 11 is shorter in length than the top chord l0, and aplurality of brace means 12 are connected at their opposite ends to thetop and bottom chords l0 and 11, respectively.

The opposite ends of the'top chord 10 extend over the upper ends of thevertical support columns C and are attached to flanges 13 on the upperends of the support columns C by means of a pluralityof bolts or rivetsor the like 14 extended through a flange 15 on the end of the top chordl0 and through the flange 13 on the tops of columns C. The columns Care. of fabricated H- section design with a web 16 extending parallel tothe axis of the beam truss T, and an, outside flange l7 and an insideflange 18. A knee brace B is connected between the opposite ends of thebottom chord 11 and the inside flange l8'of the adjacent column C at theopposite ends of the beam truss T.

Each knee brace B comprises a pair of angle members l9 and 20 bolted orotherwise suitably secured at one end thereof to one end of the bottomchord 11 on opposite sides of the web thereof. A plate 21 is welded orotherwise suitably fixed to the other end of the angle members 19 and 20at a right angle to the axes thereof and a yieldable deflection pad 22of substantially the same height and width as the plate 21 is interposedbetween the plate 21 and the inside flange 18 of the column C. Aplurality of bolts or rivets orthe like 23 extend through the plate 21and the inside flage 18 of the column to connect the knee brace B to theadjacent column C. As seen clearly in FIG. 1, a stiffening plate 24 maybe fixed between the flanges 17 and 18 of the columns C at the locationof attachment of the deflection pads to aid the columns in resisting theforce transmitted thereto through the deflection pads. In a preferredconstruction, the deflection pad is made of any suitable, commerciallyavailable elastomeric material, such as natural rubber, and has a sizeof 6 inches by 6 inches by 1 inch. The pad preferably has a durometer of70 (type A) at 70 F. and a minimum tensile strength of about 3,500 psi,and is secured with four seveneighths inch bolts in fifteen-sixteenthinch holes. Thus secured, the pad has a modulus of 3.6 ksi at 55.

As seen in FIGS. 1, 3 and 4, when a vertical load is applied to the beamtruss T as indicated by the arrows A, the bottom chord 1 l is deflectedhorizontally toward the columns C, thus exerting a compressive loadthrough the knee brace B as indicated by the arrows A. In the absence ofthe yieldable deflection pad 22, this compressive load A is exertedagainst the side of columns C, tending to bend or deflect the columns,and in some cases may overstress the column.

As viewed in FIG. 2, the beam truss T does not have any load applied toit, and the yieldable deflection pad 22 .is at its full thickness.

In FIG. 3, a vertical load is applied to the beam truss T and the bottomchord 11 is accordingly horizontally deflected, placing a compressiveforce in the knee brace B and the yieldable deflection pad 22. Thedeflection pad 22 yields or deflects commensurate with the load appliedthereto, and thus absorbs the horizontal deflection of the bottom chord,preventing bending and possible damage of the columns C, and yetproviding sufficient rigidity or stiffness to resist side sway due towind loading and the like.

In FIG. 5, a conventional beam truss T is shown subjected to a verticalload indicated by the arrows A and a compressive force A is shown beingexerted through a conventional knee brace B into the vertical supportcolumns C, and bending the columns C due to the rigid connection betweenthe ends of bottom chord 11, the knee braces B and columns C.

The present invention can be used in various combinations of trussspans, column heights and vertical and horizontal loadings to achieveeconomical design of the columns and frame construction. The yieldabledeflection pad is preferably formed of an elastomeric material havingthe capability of recovering after sustained loading and of resistingage hardening or corrosion from exposure to ozone or the like. Further,the yieldable deflection pad should be made of a material capable ofwithstanding a large percentage of compression and be operative over awide temperature range and durable even underlarge cycling of loadsthereon. In a typical installation, the deflection pad 22 has a normalthickness of about 1 inch inunloaded condition, and a thickness of lessthan 1 inch in loaded condition, depending on the amount of the load.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore il-- lustrative and not restrictive, since thescope of the invention is defined by the appended claims rather than bythe description preceding them, and all changes that fall within themetes and bounds of the claims or that form their functional as well asconjointly cooperative equivalents, are therefore intended to beembraced by those claims.

What is claimed is:

1. A frame construction for absorbing horizontal deflection of a bottomchord of a beam truss means due to vertical loading on the beam trussmeans to prevent bending of a column means on which said beam trussmeans is supported, said beam truss means having a top chord and abottom chord, the top chord of said beam truss means supported at leastat one end thereof adjacent the top of a vertically extending,I-I-section column means, knee brace means fixedly connected at one endthereof to one end of the bottom chord and extending at its outer endinto proximity with an adjacent side of said vertically extending columnmeans, an elastomeric deflection pad engaged between the other end ofsaid knee brace means and said comumn means and acting in compression toabsorb horizontal deflection of said bottom chord due to verticaldeflection of said beam truss means as a result of vertical loading onsaid beam truss means, and fastening means extended through said kneebrace means, said deflection pad and an adja-- cent portion of saidcolumn means to secure the knee brace means and deflection pad to thecolumn means, said pad thus absorbing horizontal deflections of saidbottom chord due to vertical loading on said beam truss means and thuspreventing bending of said vertically extending column means, while atthe same time the pad has sufficient rigidity to provide bracing againstside loading due to wind and the like, said H-section column meanshaving a web with oppositely directed flanges at the opposite edgesthereof, and a stiffening means secured between the flanges of thecolumn at the location of attachment of the deflection pad thereto toaid the column in resisting the force transmitted thereto through saiddeflection pad.

2. A frame construction as in claim 1, wherein said stiffening meanscomprises a plate secured between the flanges of the column.

3. A frame construction as in claim 1, wherein the top chord issupported atboth ends on the tops of a pair of vertical support columns,a knee brace extends from each of the bottom chord to the adjacent sideof an adjacent column, and a deflection pad for absorbing horizontaldeflections of said bottom chord is operatively connected with eachsaidkn ee brace.

4. A frame construction as in claim 2, wherein said bottom chord is ofsubstantially less length than said top chord and each said knee bracecomprises a pair of angle members connected at one end thereof to oneend of said bottom chord and connected at the other end thereof to theadjacent side of said vertically extending column means.

5. A frame construction as in claim 3, wherein a rectangular plate isfixed to said other end of each said knee brace at right angles to theaxis thereof, and said deflection pad is rectangular in shape andsubstantially commensurate in size with said plate, said platedistributing the conpressive loading imparted thereto from said kneebrace over the entire area of said yieldable deflection pad.

9. A frame construction as in claim 1, wherein said pad is directlyengaged at its opposite sides with said plate and with the adjacentportion of said column means, respectively.

10. A frame construction as in claim 1, wherein said deflection pad issecured in position by said fastening means is capable of absorbingsubstantially only 0cmpressive force.

t l 4 4 k

1. A frame construction for absorbing horizontal deflection of a bottomchord of a beam truss means due to vertical loading on the beam trussmeans to prevent bending of a column means on which said beam trussmeans is supported, said beam truss means having a top chord and abottoM chord, the top chord of said beam truss means supported at leastat one end thereof adjacent the top of a vertically extending, H-sectioncolumn means, knee brace means fixedly connected at one end thereof toone end of the bottom chord and extending at its outer end intoproximity with an adjacent side of said vertically extending columnmeans, an elastomeric deflection pad engaged between the other end ofsaid knee brace means and said comumn means and acting in compression toabsorb horizontal deflection of said bottom chord due to verticaldeflection of said beam truss means as a result of vertical loading onsaid beam truss means, and fastening means extended through said kneebrace means, said deflection pad and an adjacent portion of said columnmeans to secure the knee brace means and deflection pad to the columnmeans, said pad thus absorbing horizontal deflections of said bottomchord due to vertical loading on said beam truss means and thuspreventing bending of said vertically extending column means, while atthe same time the pad has sufficient rigidity to provide bracing againstside loading due to wind and the like, said H-section column meanshaving a web with oppositely directed flanges at the opposite edgesthereof, and a stiffening means secured between the flanges of thecolumn at the location of attachment of the deflection pad thereto toaid the column in resisting the force transmitted thereto through saiddeflection pad.
 2. A frame construction as in claim 1, wherein saidstiffening means comprises a plate secured between the flanges of thecolumn.
 3. A frame construction as in claim 1, wherein the top chord issupported at both ends on the tops of a pair of vertical supportcolumns, a knee brace extends from each of the bottom chord to theadjacent side of an adjacent column, and a deflection pad for absorbinghorizontal deflections of said bottom chord is operatively connectedwith each said knee brace.
 4. A frame construction as in claim 2,wherein said bottom chord is of substantially less length than said topchord and each said knee brace comprises a pair of angle membersconnected at one end thereof to one end of said bottom chord andconnected at the other end thereof to the adjacent side of saidvertically extending column means.
 5. A frame construction as in claim3, wherein a rectangular plate is fixed to said other end of each saidknee brace at right angles to the axis thereof, and said deflection padis rectangular in shape and substantially commensurate in size with saidplate, said plate distributing the conpressive loading imparted theretofrom said knee brace over the entire area of said yieldable deflectionpad.
 6. A frame construction as in claim 5, wherein said deflection padis made of natural rubber.
 7. A frame construction as in claim 6,wherein said deflection pad has a size of 6 inches by 6 inches by 1 inchand is secured with four seven-eights inch bolts extended throughfifteen-sixteenths inch holes.
 8. A frame construction as in claim 7,wherein the deflection pad has a durometer of 70 (type A) at 70F, aminimum tensile strength of 3,500 psi, and a modulus of 3.6 ksi at 55*.9. A frame construction as in claim 1, wherein said pad is directlyengaged at its opposite sides with said plate and with the adjacentportion of said column means, respectively.
 10. A frame construction asin claim 1, wherein said deflection pad is secured in position by saidfastening means is capable of absorbing substantially only ocmpressiveforce.